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R290 top up

Hi guys new to this site,
Looking for advice on r290 , I've never worked on this before in my many years I've been in the trade, but came across a fosters fridge the other day that was sat at 28 degrees, everything was working (evap/cond fans, comp etc) pressures where -11inhg low side and 50psi high side , after researching what the running pressures should be I've come to the conclusion it's low on gas, I've arranged to pressure test and recharge but the drier is in the most horrendous place as is almost impossible to replace and braze with out burning the side panel which cannot be removed,
Would anyone just Risk not changing the drier ? And please correct me if any of my assumptions on the pressures are wrong
Thanks

Re: R290 top up

Maybe advisable to get a basic 1/2 HC course under your belt to ensure your up on the safety side of these refrigerants. A1 rated evacuation pump and recovery machines required.
R290, as with other HC known to readily mix with oil which moves through the system freely. On integral type systems such as a Foster unit, blocked drivers are not un common I believe.
I would cut out the drier and blow through the system with OFN as part of the repair process to eliminate a blocked drier.
As with HFC Foster units some times the 1/4 pipe, drier , capillary assembly can be manipulated into a more easily accessible position to cut out the drier, and a new item soldered in.
For safety purge through entire system with OFN to remove all traces of R290 prior to undertaking any hot work.

Re: R290 top up

Condensors block with dirt then block capillarys prone to this fault we have had same issues with access either reposition drier or use lock rings we tend to use lock rings more on the flammable gas as I like my eyebrows !

Re: R290 top up

Thanks for your helpful reply Yes I think I'm going to arrange a HC course for future reference, but for the time being I will wheel the fridge outside and let the gas go into the atmosphere then chop out the drier and try re position it, Inwill have to make do with my standard vacuum pump this time (hoping that is safe to use)

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